Compare and contrast the five generations of cephalosporins

2nd
1. Activity -Variable activity against gram positive bacteria but increased activity against gram negative bacteria
2. Structural features and chemistry- Broader spectrum of activity than most first generation due to greater steric hindrance provided by the methoxy group
  1. Cefoxitin - Methoxy substituent at position 7 (steric hindrance) – Urethane group ( good metabolic stability to esterase )
  2. Cefuroxime – Iminomethoxy group at alpha position of the acyl side chain ( Increase resistance to B-lactamases and mammalian esterases)
4th
1. Activity- Broadest spectrum of activity, with similar activity against gram-positive organisms as first generation cephalosporins. Greater resistance to beta-lactamases than the third generation cephalosporins
2. Structural feature and chemistry- Cefepime and Cefpirome– Zwitterionic compounds (radically enhance the ability to penetrate outer membrane of Gram negative bacteria, good affinity for transpeptidase enzyme, low affinity for variety of B-lactamases)
3rd
1. Activity- Broad spectrum and the effective against both gram positive and gram negative bacteria. Optimum activity is against gram negative bacteria.
2. structural features and chemistry-Ceftazidime- aminothiazole ring enhances the penetration through lipopolysaccharide and increase affinity for transpeptidase
1st
1. Activity- Effective against gram positive bacteria and have little effect against gram negative bacteria.
2. structural features and chemistry
  1. Cephaloridine – pyridinium group at position 3 (good leaving group, not readily hydrolysed by esterase)
  2. Cephalothin- acetyoxy group at position 3 (good leaving group but is readily hydrolysed by esterase)
  3. Cefalexin – Methyl substituent at position 3 (not good leaving group but help oral absorption) -Hydrophilic amino group at 7-acylamino side chain (compensate bad activity)
5th
1. Activity- Broad spectrum activity against gram negative bacteria such as MRSA
2. structural features and chemistry- a bicyclic ring with four-member β-lactam ring fused to a six-member cephem ring
  1. Ceftaroline- thiazolylthio group cause the activity against MRSA
Side effects
1. 6. a) bleeding disorders b) Flushing, tachycardia, vomiting with alcohol intake (cefamandole, moxalactam & cefoperazone)
2. 1. Hypersensitivity reactions
3. 2. Nephrotoxicity (cephradine)
4. 3. Thrombophlebitis ( i.v admin.)
5. 4. Superinfections
6. 5. Diahea (oral cephalosporins, cefoperazone, ceftriaxone & moxalactam)

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Compare and contrast the five generations of cephalosporins

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